In recent years, the image recording material is predominated particularly by a material for forming a color image. More specifically, an inkjet system recording material, a thermal transfer-type image recording material, a recording material using an electrophotographic system, a transfer system silver halide photographic material, a printing ink, a recording pen and the like are popularly used.
In these color image recording materials, three primary color dyes (dyes or pigments) for a so-called subtractive color mixing method are used for reproducing or recording a full color image, however, a dye having absorption properties capable of realizing a preferred color reproduction region and having fastness capable of enduring various use conditions is not found at present and improvements are keenly demanded.
The inkjet recording method has been abruptly spread and is further growing because the material cost is low, high-speed recording can be obtained, noises are less generated at the recording and color recording is easy.
The inkjet recording method includes a continuous system of continuously jetting out a liquid droplet and an on-demand system of jetting out a liquid droplet according to image information signals, and the ejection system therefor includes a system of ejecting a liquid droplet by applying a pressure using a piezoelectric element, a system of ejecting a liquid droplet by generating bubbles in ink using heat, a system of using an ultrasonic wave, and a system of ejecting a liquid droplet by suction using an electrostatic force. The ink used for inkjet recording includes an aqueous ink, an oily ink and a solid (fusion-type) ink.
The coloring agent used in such an inkjet recording ink is required to have high solubility or dispersibility in a solvent, enable high-density recording, provide good color, be fast to light, heat and active gases in the environment (for example, NOx, oxidative gas (e.g., ozone) and SOx), exhibit excellent fastness to water and chemicals, ensure good fixing to an image-receiving material and less bleeding, give an ink having excellent storability, have high purity and no toxicity, and be available at a low cost. However, it is very difficult to find out a coloring agent satisfying these requirements in a high level. In particular, the coloring agent is strongly demanded to ensure good color for three primary colors, be fast to light, humidity and heat and at the printing on an image-receiving material having an ink-accepting layer containing a porous white inorganic pigment particle, be resistant against oxidative gases such as ozone in the environment.
Conventionally, azo dyes using a phenol, a naphthol or an aniline as the coupling component have been widely used as the dye. However, these dyes all are very poor in the fastness to oxidative gases such as ozone.